GoKawiilThe potential benefits of organoids for fundamental research and medicine are huge. Efforts to establish proper boundaries for their use should be supported.
Tiny spheres of brain-like structures called organoids can be used to study neurodevelopmental conditionsCredit: S. Pasca Lab/Stanford University
The ‘brain in a jar’ is one of science fiction’s most enduring tropes. Stripped of its body but not of its will, the isolated brain is most often portrayed as a malevolent force, able to impose its evil intentions on the world through proxies.
This is implausible fantasy. But, on a smaller scale and in the real world, researchers can now make tiny, functioning models of parts of the brain known as organoids. The science has come on in leaps and bounds in little more than a decade, as a News Feature in this week’s issue lays out. Brain organoids will be a force for good — for fundamental research, medicine and helping us to understand what makes us human. But as neuroscientists strive for greater improvements to better mimic particular brain systems, ethical and social considerations of the work are becoming apparent that require serious — and prompt — attention. Efforts to start public discussions should be welcomed and supported, so that appropriate guidelines are in place before they are needed.
Mini models of the human brain are revealing how this complex organ takes shape
Brain organoids are tiny spheres of simple brain-like structures that are made from human stem cells. They self-organize in a dish much as they would during development and provide a much-needed source of research material. Access to human brain tissue is otherwise scarce; other animals make poor substitutes and conventional 2D cultures of brain cells cannot address issues of how the brain develops and functions in its accustomed 3D space.
Improved techniques have allowed organoids to be made more reliably and endowed with ever-greater complexity, representing several brain areas. As a result, neuroscientists are slowly beginning to piece together the vast and intricate sequence of molecular steps that underlie human brain development in the womb. Researchers are using human brain organoids to help understand, and even develop treatments for, a range of genetic and neurodevelopmental conditions.
But, as useful as brain organoids are, they are not free of ethical challenges. Human brain organoids obviate the need for a lot of animal research, but it can be difficult to keep them functioning optimally in culture for a sustained period of time. Some scientists transplant them into the brains of living rodents, which provide supportive and more natural environments for longer-term development. Further research will be needed to determine the effects of human and rodent brain tissues interacting in this way. There is a lot of unease among researchers about breaching the boundary between humans and other animals for brain tissue. Guidelines for how such studies should be done and where the appropriate ethical boundaries lie must be determined now.
The age of animal experiments is waning. Where will science go next?
Perhaps most crucially for this field is the concern that emergent properties, such as consciousness, might arise in complex organoids. So far, there has been no evidence that any form of sentience could emerge, but researchers would like this to be monitored continuously.
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